The latest from the MySQL community

Author: Robert Agar

One of the tasks that a database team needs to be prepared to perform is a MySQL migration. In the deep, dark past of the early 21st Century, this would have involved moving a MySQL database from one server to another one located within your company’s data center. This might have been done to take advantage of better hardware with which to provide optimal service to the database’s end users. As the IT needs of a business change, systems are often shuffled around to make the best use of computing resources.

Besides enjoying the faster performance the main impact of migration on your database team is the requirement to use a different IP address to connect to the server hosting the databases they support. No big deal. The assumption would be that all tools and monitoring platforms in place before the migration will continue to function correctly. Once the dust settles, all is well in …

In MySQL and Oracle, you set a session variable quite differently. That means you should expect there differences between setting a session variable in Postgres. This blog post lets you see how to set them in all three databases. I’m always curious what people think but I’m willing to bet that MySQL is the simplest approach. Postgres is a bit more complex because you must use a function call, but Oracle is the most complex.

The difference between MySQL and Postgres is an “@” symbol versus a current_setting() function call. Oracle is more complex because it involves the mechanics in Oracle’s sqlplus shell, SQL dialect, and PL/SQL language (required to assign a value to a variable).

MySQL

MySQL lets you declare a session variable in one step and use it one way in a SQL statement or stored procedure.

1. You set a session variable on a single line with the following …

When building network libraries for Node.js, as we do at work, one quite quickly comes by Node's Buffer type. A Buffer gives access to a memory region in a quite raw form, allowing to handle raw data and allowing to interpret binary streams. The Buffer interface predates ES6 TypedArrays and has some optimizations.

Two optimisations are notable:

For one the slice() method does not copy data, but returns a view on the underlying data. This makes it quite efficient to work on a window of the data, but when writing one has to be careful. Simple example:

const buffer = Buffer.from("hello"); …

MySQL Shell is a pretty nice piece of software. Is not just another mysql client but it is also a tool that offers scripting capabilities for JavaScript and Python. And one of the coolest things you can do with it is to check if your MySQL 5.7 server is ready for an upgrade or not. Enter: Upgrade Checker Utility.

MySQL Shell Upgrade Checker Utility

So what is it? It is a script that will check your MySQL 5.7 instance for compatibility errors and issues with upgrading. It’s important to notice the word “check”. It doesn’t fix. Just check. Fix is on you, friendly DBA (or we can happily assist with it).

But isn’t there something that already does that? Close, but no. The mysqlchk program and the –check-upgrade parameter does something similar: Invokes the CHECK TABLE …. FOR UPGRADE command. The Upgrade …

Multiplexing Background

Historically it’s a technique used in networking to integrate multiple analog and digital signals via a shared medium. The goal of multiplexing over the network was to enable signals to be transmitted more efficiently for a given communication channel, thus achieving cost efficiency. 

Since the term Multiplexing comes from telecommunications, the industry has heavily used a device called Multiplexers – aka Mux. There was even a term called muxing where signals were often analog and digital to be combined in a single line. 

The technique was developed in the early 1870s, it’s origins to be found in telegraphy, and it has become a standard for digital telecommunications in the 20th Century. 

Following multiplexing methods are currently available: 

• Frequency Division Multiplexing (FDM)
• Time Division Multiplexing (TDM) …

MySQL 8 does not yet support the BOOLEAN type as specified in the SQL standard. There is a DDL "type" called BOOL, which is just an alias for TINYINT: create table t(b bool); select table_name, column_name, data_type, column_type from information_schema.columns where table_name = 't'; The above produces: TABLE_NAME|COLUMN_NAME|DATA_TYPE|COLUMN_TYPE| ----------|-----------|---------|-----------| t |b |tinyint |tinyint(1) | Notice … Continue reading How to Map MySQL’s TINYINT(1) to Boolean in jOOQ →

SQL CONCAT_WS Function Example | CONCAT_WS Method In SQL is today’s topic. The SQL CONCAT_WS function is used to join two or more expressions separated by a separator. It takes up to 255 input strings which are further joined by a function. If we want to perform the join operation, CONCAT requires at least 2 strings. If it is provided with only 1 string, it will raise the error.

SQL CONCAT_WS Function

If any non-character string values are passed into the function, it will be implicitly converted to the strings before concatenating.

If NULL is added to the function, it converts it into the empty string with VARCHAR (1).

See the following syntax.

SELECT CONCAT_WS (separator, expression1, expression2, expression3…)

Parameters Separator

We just wrapped up what was a very exciting OOW 2019 - San Francisco for MySQL.  Our MySQL track included 29 sessions, a keynote with 2 customer testimonials (Mercari and WePay), 1 tutorial, 1 Hands-on lab, 1 Birds of a Feather, and our always fun and enjoyable MySQL Community Reception.  

A BIG Thank You to the companies who came to share their experience and testimonial about how MySQL helps scale their company such as Facebook, JP Morgan Chase WePay, Credorax, Mercari, Zuora, and more.

Our focus this year: SECURITY.  With 3,800 breaches and over 4 Billion Records Stolen in just H1 2019, securing data has become a priority for any business. The first part of the keynote covers the new security features from Oracle and MySQL implemented in our latest version of the Enterprise Edition.

Other highlights for MySQL:

• MySQL 8.0,  fastest adoption of any version with over 26% …

In a previous post, I showed you how to compile Percona Mysql 5.7 on Raspberry PI 3. Now, I’ll show you how to compile and run the latest version of Percona XtraDB Cluster 5.7.26.

We will need at least 3 RaspberryPi 3 boards, and I recommend you use an external SSD drive to compile and use as MySQL’s “datadir” to avoid the stalls associated with the microSD card, which will cause PXC to run slow.

In this post, we are going to run many OS commands and configure PXC. I recommend having minimal knowledge about PXC and Linux commands.

How to install CentOS

Download the centos image from this link …

Overview The Skinny

In this blog post we explore various options for performance tuning MySQL server for better slave replication performance.

A Tungsten Cluster relies upon the Tungsten Replicator to move events from the master node to the slaves. Once the event has been transferred to the slave as THL on disk, the slave applier will then attempt to write it to the database. The Replicator can only apply events as fast as MySQL allows. If the MySQL server is somehow slow or blocking, then the Replicator will be as well.

A properly-tuned database server in addition to infrastructure and SysAdmin best practices will go quite a long way towards high-performance slave apply.

The Question Recently, a customer asked us:

During one of our load tests, we had a peak of 60k writes/min, averaging …